Pesticide and Environmental Update
Luring
Varroa Mites to Their Doom
 Varroa
mites in a cell of a honey bee comb that has been treated with attractants
identified by chemist Peter Teal and collaborators. The other cells (with
no mites) are control cells (no attractants). (D1506-1)
The Varroa mite, Varroa destructor, is only about one-sixteenth of an
inch long. But that hasn’t stopped the eight-legged, blood-sucking
parasite from becoming the single worst pest of honey bees since first
being detected in Florida in the 1980s.
Any threat to honey bees is a threat to American agriculture. Without
them, the yield and quality of many flowering crops would suffer—almonds,
apples, blueberries, cantaloupe, cranberries, and zucchini, to name just a
few. Indeed, as the chief pollinator of these crops, the honey bee’s
contributions are considered a $14 billion asset to our economy—and that’s
not even counting the honey and beeswax the insect produces.
So it is with quite a bit of urgency that researchers nationwide are
seeking new ways to control Varroa, particularly methods that will
diminish reliance on the chemical controls—fluvalinate and coumaphos—now
used. At the ARS Chemistry Research Unit in Gainesville, Florida, research
leader Peter E.A. Teal is testing a bait-and-kill approach using sticky
boards dosed with natural chemical attractants, called “semiochemicals.”
For patenting reasons, Teal won’t reveal what the specific compounds
are, other than to say they’re naturally produced by honey bees and
highly attractive to Varroa mites.
In nature, Varroa mites rely on the semiochemicals to locate—and then
feed on the bloodlike hemolymph of—both adult bees and their brood,
weakening or killing them. Severe infestations can decimate an affected
hive within several months—and rob the beekeeper of profits from honey
or pollinating services. But in this case, the mites encounter a more
heady bouquet of honey bee odors that lure them away from their intended
hosts and onto the sticky boards, where they starve.
Preliminary tests of the attractant have been promising. “For
example, we are able to induce 35 to 50 percent of mites to drop off of
bees when we present them with either of the two attractants, and more
than 60 percent of free mites are attracted to these chemicals in
biological tests,” Teal reports. Moreover, it doesn’t appear that the
extra dose of semiochemicals wafting through the hive interferes with the
honey bees’ normal behavior or activity to any significant degree, adds
Teal, who, along with postdoctoral associate Adrian Duehl and University
of Florida collaborator Mark J. Carroll, reported the results this past
January at the 2009 North American Beekeeping Conference in Reno, Nevada.
The researchers hope ARS’s patenting of the Varroa attractants will
encourage an industrial partner to develop the technology further for use
by beekeepers as both a monitoring tool and an alternative to chemical
controls.—By Jan Suszkiw, Agricultural Research Service Information
Staff.
This research is part of Crop Protection and Quarantine, an ARS
national program (#304) described on the World Wide Web at
www.nps.ars.usda.gov.
Peter E.A. Teal is in the USDA-ARS Chemistry Research Unit, Center for
Medical, Agricultural, and Veterinary Entomology, 1600-1700 S.W. 23rd Dr.,
Gainesville, FL 32608; phone (352) 374-5730, fax (352) 374-5707.
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